Invert Binary Tree

https://leetcode.com/problems/invert-binary-tree/

4
/   \
2     7
/ \   / \
1   3 6   9

4
/   \
7     2
/ \   / \
9   6 3   1

直接用递归

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def invertTree(self, root):
"""
:type root: TreeNode
:rtype: TreeNode
"""
if root:
root.left,root.right = root.right,root.left
self.invertTree(root.left)
self.invertTree(root.right)
return root